A significant problem with previous devices for dispensing ophthalmic solutions is contamination of the dropper nozzle by inadvertent contact with the eye and other surfaces. The problem is described by Hovding et al., Acta Opthalmologica, 60: 213-222 (1982). This contact also can clog the orifice of the tip, making it impossible to dispense further drops. Contamination of the nozzle can then result in microbial contamination of the solution remaining in the dropper bottle and the transfer of this contamination to either or both eyes.
One common route of this contamination comprises touching the dropper nozzle to the surface of the eye during administration of medication. The contact permits contamination of the fluid remaining in the nozzle, which liquid ultimately flows back into the dropper bottle, contaminating the entire contents, and sometimes eventually plugging the dispenser tip.
Some devices have been reported which serve to prevent contact of a dropper nozzle but which were designed primarily to aid in aiming the dropper nozzle properly. See for example U.S. Pat. Nos. 4,834,728; 3,945,381; 4,111,200 and 4,733,802. These devices generally comprise a large cup-shaped or cone-shaped member, the rim of which rests on the patient's face over the eye socket and have a tip composed of a nozzle protruding through the cup-shaped member oriented so that drops from the nozzle will enter the eye.
These reported devices are fairly large, cumbersome and not easily carried in a handbag or pocket. The diameter of the cup-shaped member is large enough to permit easy contact of the dropper tip with fingers or other septic objects resulting in contamination of the device and its contents. Furthermore, covering of the eye with the large cup-shaped member may actually increase the blink reflex, thus raising the likelihood that the drop will miss the intended target.